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	$198.51	12.193%	$222.7143	$222.71	$222.70	$222.70
Purchase #2	$16.50	11.581%	$18.4109	$18.41	$18.40	$18.40
Purchase #3	$68.67	4.610%	$71.8357	$71.84	$71.85	$71.80
Purchase #4	$233.69	12.592%	$263.1162	$263.12	$263.10	$263.10
Purchase #5	$124.74	5.643%	$131.7791	$131.78	$131.80	$131.80
Purchase #6	$167.34	4.214%	$174.3917	$174.39	$174.40	$174.40
Purchase #7	$135.65	4.747%	$142.0893	$142.09	$142.10	$142.10
7 purchase totals =	$945.10		$1,024.3372	$1,024.34	$1,024.35	$1,024.30