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	$75.95	3.552%	$78.6477	$78.65	$78.65	$78.60
Purchase #2	$85.71	5.402%	$90.3401	$90.34	$90.35	$90.30
Purchase #3	$177.52	10.502%	$196.1632	$196.16	$196.15	$196.20
Purchase #4	$28.77	5.471%	$30.344	$30.34	$30.35	$30.30
Purchase #5	$202.41	11.583%	$225.8552	$225.86	$225.85	$225.90
Purchase #6	$210.93	10.425%	$232.9195	$232.92	$232.90	$232.90
Purchase #7	$157.40	6.222%	$167.1934	$167.19	$167.20	$167.20
7 purchase totals =	$938.69		$1,021.4631	$1,021.46	$1,021.45	$1,021.40