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	$190.59	3.799%	$197.8305	$197.83	$197.85	$197.80
Purchase #2	$183.48	6.850%	$196.0484	$196.05	$196.05	$196.00
Purchase #3	$180.32	10.308%	$198.9074	$198.91	$198.90	$198.90
Purchase #4	$65.25	7.190%	$69.9415	$69.94	$69.95	$69.90
Purchase #5	$173.69	10.222%	$191.4446	$191.44	$191.45	$191.40
Purchase #6	$89.62	13.326%	$101.5628	$101.56	$101.55	$101.60
Purchase #7	$56.32	5.306%	$59.3083	$59.31	$59.30	$59.30
7 purchase totals =	$939.27		$1,015.0435	$1,015.04	$1,015.05	$1,014.90