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	$191.69	10.683%	$212.1682	$212.17	$212.15	$212.20
Purchase #2	$177.75	11.873%	$198.8543	$198.85	$198.85	$198.90
Purchase #3	$53.32	11.362%	$59.3782	$59.38	$59.40	$59.40
Purchase #4	$66.31	3.415%	$68.5745	$68.57	$68.55	$68.60
Purchase #5	$146.63	8.865%	$159.6287	$159.63	$159.65	$159.60
Purchase #6	$179.29	6.454%	$190.8614	$190.86	$190.85	$190.90
Purchase #7	$222.27	6.518%	$236.7576	$236.76	$236.75	$236.80
7 purchase totals =	$1,037.26		$1,126.2229	$1,126.22	$1,126.20	$1,126.40