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	$152.86	3.498%	$158.207	$158.21	$158.20	$158.20
Purchase #2	$42.86	5.539%	$45.234	$45.23	$45.25	$45.20
Purchase #3	$196.58	11.348%	$218.8879	$218.89	$218.90	$218.90
Purchase #4	$232.61	13.758%	$264.6125	$264.61	$264.60	$264.60
Purchase #5	$74.96	11.514%	$83.5909	$83.59	$83.60	$83.60
Purchase #6	$157.96	7.628%	$170.0092	$170.01	$170.00	$170.00
Purchase #7	$163.91	13.455%	$185.9641	$185.96	$185.95	$186.00
7 purchase totals =	$1,021.74		$1,126.5056	$1,126.50	$1,126.50	$1,126.50