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	$186.31	5.161%	$195.9255	$195.93	$195.95	$195.90
Purchase #2	$102.39	3.751%	$106.2306	$106.23	$106.25	$106.20
Purchase #3	$143.80	8.148%	$155.5168	$155.52	$155.50	$155.50
Purchase #4	$176.54	9.146%	$192.6863	$192.69	$192.70	$192.70
Purchase #5	$191.31	12.518%	$215.2582	$215.26	$215.25	$215.30
Purchase #6	$106.65	5.610%	$112.6331	$112.63	$112.65	$112.60
Purchase #7	$34.44	11.165%	$38.2852	$38.29	$38.30	$38.30
7 purchase totals =	$941.44		$1,016.5357	$1,016.55	$1,016.60	$1,016.50