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	$50.94	7.117%	$54.5654	$54.57	$54.55	$54.60
Purchase #2	$184.76	6.499%	$196.7676	$196.77	$196.75	$196.80
Purchase #3	$170.54	13.435%	$193.452	$193.45	$193.45	$193.50
Purchase #4	$40.95	6.133%	$43.4615	$43.46	$43.45	$43.50
Purchase #5	$136.29	10.470%	$150.5596	$150.56	$150.55	$150.60
Purchase #6	$249.44	7.277%	$267.5917	$267.59	$267.60	$267.60
Purchase #7	$181.87	3.727%	$188.6483	$188.65	$188.65	$188.60
7 purchase totals =	$1,014.79		$1,095.0461	$1,095.05	$1,095.00	$1,095.20