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	$127.65	4.637%	$133.5691	$133.57	$133.55	$133.60
Purchase #2	$162.81	10.123%	$179.2913	$179.29	$179.30	$179.30
Purchase #3	$46.41	8.478%	$50.3446	$50.34	$50.35	$50.30
Purchase #4	$156.63	5.722%	$165.5924	$165.59	$165.60	$165.60
Purchase #5	$48.59	10.870%	$53.8717	$53.87	$53.85	$53.90
Purchase #6	$219.62	6.106%	$233.03	$233.03	$233.05	$233.00
Purchase #7	$186.69	10.714%	$206.692	$206.69	$206.70	$206.70
7 purchase totals =	$948.40		$1,022.3911	$1,022.38	$1,022.40	$1,022.40