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	$159.56	6.336%	$169.6697	$169.67	$169.65	$169.70
Purchase #2	$151.31	7.206%	$162.2134	$162.21	$162.20	$162.20
Purchase #3	$43.26	4.552%	$45.2292	$45.23	$45.25	$45.20
Purchase #4	$228.41	6.624%	$243.5399	$243.54	$243.55	$243.50
Purchase #5	$138.94	12.377%	$156.1366	$156.14	$156.15	$156.10
Purchase #6	$181.91	3.118%	$187.582	$187.58	$187.60	$187.60
Purchase #7	$57.77	7.544%	$62.1282	$62.13	$62.15	$62.10
7 purchase totals =	$961.16		$1,026.4990	$1,026.50	$1,026.55	$1,026.40