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	$174.34	12.534%	$196.1918	$196.19	$196.20	$196.20
Purchase #2	$221.94	7.508%	$238.6033	$238.60	$238.60	$238.60
Purchase #3	$62.86	13.607%	$71.4134	$71.41	$71.40	$71.40
Purchase #4	$219.90	12.599%	$247.6052	$247.61	$247.60	$247.60
Purchase #5	$55.92	4.364%	$58.3603	$58.36	$58.35	$58.40
Purchase #6	$156.92	6.200%	$166.649	$166.65	$166.65	$166.60
Purchase #7	$71.90	7.665%	$77.4111	$77.41	$77.40	$77.40
7 purchase totals =	$963.78		$1,056.2341	$1,056.23	$1,056.20	$1,056.20