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	$191.57	4.727%	$200.6255	$200.63	$200.65	$200.60
Purchase #2	$19.89	6.273%	$21.1377	$21.14	$21.15	$21.10
Purchase #3	$176.94	13.478%	$200.788	$200.79	$200.80	$200.80
Purchase #4	$11.76	6.729%	$12.5513	$12.55	$12.55	$12.60
Purchase #5	$248.65	8.474%	$269.7206	$269.72	$269.70	$269.70
Purchase #6	$226.44	7.486%	$243.3913	$243.39	$243.40	$243.40
Purchase #7	$73.72	6.865%	$78.7809	$78.78	$78.80	$78.80
7 purchase totals =	$948.97		$1,026.9953	$1,027.00	$1,027.05	$1,027.00