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	$223.28	6.773%	$238.4028	$238.40	$238.40	$238.40
Purchase #2	$195.82	10.500%	$216.3811	$216.38	$216.40	$216.40
Purchase #3	$77.31	6.148%	$82.063	$82.06	$82.05	$82.10
Purchase #4	$61.72	5.538%	$65.1381	$65.14	$65.15	$65.10
Purchase #5	$51.44	3.259%	$53.1164	$53.12	$53.10	$53.10
Purchase #6	$103.60	12.275%	$116.3169	$116.32	$116.30	$116.30
Purchase #7	$237.60	7.283%	$254.9044	$254.90	$254.90	$254.90
7 purchase totals =	$950.77		$1,026.3227	$1,026.32	$1,026.30	$1,026.30