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	$185.27	8.730%	$201.4441	$201.44	$201.45	$201.40
Purchase #2	$39.81	9.642%	$43.6485	$43.65	$43.65	$43.60
Purchase #3	$206.53	8.362%	$223.8	$223.80	$223.80	$223.80
Purchase #4	$79.64	3.591%	$82.4999	$82.50	$82.50	$82.50
Purchase #5	$245.88	11.399%	$273.9079	$273.91	$273.90	$273.90
Purchase #6	$59.76	10.212%	$65.8627	$65.86	$65.85	$65.90
Purchase #7	$153.43	11.550%	$171.1512	$171.15	$171.15	$171.20
7 purchase totals =	$970.32		$1,062.3143	$1,062.31	$1,062.30	$1,062.30