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	$244.76	9.401%	$267.7699	$267.77	$267.75	$267.80
Purchase #2	$24.26	6.713%	$25.8886	$25.89	$25.90	$25.90
Purchase #3	$31.80	12.340%	$35.7241	$35.72	$35.70	$35.70
Purchase #4	$141.72	10.455%	$156.5368	$156.54	$156.55	$156.50
Purchase #5	$37.93	3.603%	$39.2966	$39.30	$39.30	$39.30
Purchase #6	$230.76	5.592%	$243.6641	$243.66	$243.65	$243.70
Purchase #7	$55.36	7.102%	$59.2917	$59.29	$59.30	$59.30
7 purchase totals =	$766.59		$828.1718	$828.17	$828.15	$828.20