Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$211.64	4.767%	$221.7289	$221.73	$221.75	$221.70
Purchase #2	$69.38	12.874%	$78.312	$78.31	$78.30	$78.30
Purchase #3	$211.54	5.526%	$223.2297	$223.23	$223.25	$223.20
Purchase #4	$115.84	13.565%	$131.5537	$131.55	$131.55	$131.60
Purchase #5	$176.27	5.316%	$185.6405	$185.64	$185.65	$185.60
Purchase #6	$224.37	10.365%	$247.626	$247.63	$247.65	$247.60
Purchase #7	$215.61	12.582%	$242.7381	$242.74	$242.75	$242.70
7 purchase totals =	$1,224.65		$1,330.8289	$1,330.83	$1,330.90	$1,330.70